SEM and XRD Characterization of Ni-Hf Alloys at Low Hf Concentration

Abstract:

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The alloying and phase formation in Ni-Hf samples with 0.2-, 2-, and 5-at.% Hf were
studied by X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). Both
characterization methods, XRD and SEM, reveal the presence of the HfNi5 phase (fcc structure)
where the excess Ni atoms are present in the form of Ni or Ni-rich segregations in the sample
containing 5-at.% Hf. The sample with 2-at.% Hf is characterized by the presence of the two phases
present in the 5-at.% sample and by Hf atoms, which occupy substitutional lattice positions in the
Ni lattice. Finally, in the third sample with 0.2-at.% Hf, the Hf atoms mainly substitute the Ni atoms
in the lattice. This analysis is being complemented with additional information on the local structure
around Hf by extended X-ray absorption fine structure spectroscopy (EXAFS).

Abstract: A combustion front quenching (CFQ) technique was used to investigate the mechanism of selfpropagating high-temperature synthesis (SHS) of MoSi2 from Mo and Si powders. Based on the experimental results, a combination of reactive diffusion and dissolution-precipitation mechanism of the formation of MoSi2 was proposed, and a model corresponding to this mechanism was drawn.

Abstract: This paper presents the work on the development of ceramic coating processing.
Nano-structured zirconia coating has been developed with functions; substrate temperature and
oxygen gas change in chamber by electron beam physical vapor deposition (EB-PVD). The
microstructure of the coating layer has been characterized with FE-SEM, and SEM. The crystalline
phase of the coating layer has been also characterized with XRD. The zirconia coating by EB-PVD
had not monoclinic zirconia phase as shown in XRD pattern and Raman spectra and the thickness of
coating were quite homogeneous. The fracture microstructure of the coating layer for a thickness of
~15 μm showed columnar or non-columnar structure and had nano-structure with nano scaled grain as
shown in micrograph by FE-SEM.

Abstract: Amorphous calcium silicate coating on a metallic titanium substrate for hard tissue
replacement was prepared by a sol-gel method. Calcium silicate film was deposited on a titanium
substrate by a spin-coating technique and subsequently heated at 500°C for 2 h in air. The deposited
film, which was dense, had thickness of about 800 nm and strongly adhered to the substrate.
Biomimetic apatite-forming ability of the deposited films was examined by soaking in simulated body
fluid (SBF). Thin film X-ray diffractometry and scanning electron microscopy showed the formation
of apatite on the surface after 10 days of soaking in SBF.

Abstract: α-MoO3 microspheres assembled by nanorods were synthesized in room temperature ionic liquids (bmimBF4: 1-butyl-3-methylimidazolium tetrafluoroborate) by microwaves heating method. The microstructure and morphology of the products were characterized by the techniques of X-ray powder diffraction (XRD), Fourier-transform spectrometer (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM). The influence factor such as the amount of ammonium heptamolybdenum tetrahydrate in ionic liquids was investigated in detail. The possible reaction mechanism was also discussed. It was demonstrated that the ionic liquid could act as template agent for the formation of α-MoO3 microspheres. The present synthesis route is very simple and fast, and could be extended to the fabrication of other nanomaterials in ionic liquids.

Abstract: Monodisperse α-Fe2O3 nanoparticles with average particle size of 110 nm were successfully prepared using olyvinylpyrrolidone (PVP) as surfactant via a novel hydrothermal route. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The experiments results revealed that PVP and the concentration of NH4HCO3 have played a crucial role in the formation of the monodisperse a-Fe2O3 nanoparticles.